"Can try to describe it. Might be easier to do with time on paper, but I'll give it my best shot now while you can ask questions as soon as they come up... Mine is largely cribbed off of my shadow-stepping because it's easier for me to fit it in my head that way. More efficient teleportation - less energy cost, it would also probably help with range - would go through the Astral plane instead of the plane of shadows so I'd suggest you try developing it that way from the start."
And they launch into an explanation, osanwë'ing the sensation of teleporting - if Curufin's learned basic divination then he can detect magic while they demonstrate, for an outside view. Curufin has plenty of questions, and Malak answers them more confidently than before - they paid more attention to the development process this time for precisely this reason.
A few hours later it seems about as explained as it's going to get and Malak heads back to their room to read over Curufin's notes on the elven spell development. Unless Celegorm is currently around and they can test things with Huan.